Background: Tardive dyskinesia (TD) is a significant clinical problem. Vitamin B6 is a potent antioxidant and takes part in almost all of the possible mechanisms that are suggested as being associated with appearance of TD. The aims of this study were (1) to reexamine the efficacy and safety of higher doses of vitamin B6 versus placebo in a greater sample of patients for a longer time and (2) to evaluate the carryover effect of vitamin B6.

Method:A 26-week, double-blind, placebo-controlled trial was conducted in a university-based research clinic from August 2002 to January 2005 on 50 inpatients with DSM-IV diagnoses of schizophrenia or schizoaffective disorder and TD. In a double-blind crossover paradigm, all study subjects were randomly assigned to start treatment with either vitamin B6 (daily dose of 1200 mg) or placebo. After 12 weeks of treatment and then a 2-week washout, subjects were crossed over to receive the other treatment for 12 weeks. The primary outcome measure was the change from baseline in Extrapyramidal Symptom Rating Scale (ESRS) scores.